Communication equipment communicating in a licensed frequency band identifies unused unlicensed communication resources within an unlicensed frequency band. The communication equipment uses the identified unlicensed communication resources to communicate within the unlicensed frequency band. In some circumstances, the unused unlicensed communication resources are identified based on resource information received from a base station where the resource information identifies unlicensed communication resources that will be used by the base station. In other circumstances, the unused unlicensed communication resources are identified based on frequency band measurements of the unlicensed frequency band over an observation time duration longer than a sensing time duration used by unlicensed equipment using the unlicensed frequency band.
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8. A base station comprising:
a transceiver configured to:
transmit to a user equipment (UE) measurement configuration information via a licensed frequency band, wherein the measurement configuration information is information to instruct the UE to perform measurements on an unlicensed frequency band, and
receive measurement results from the UE, wherein the measurement results include Received signal strength Indicator (RSSI) values of the unlicensed frequency band; and
wherein the transceiver is further configured to:
transmit, to the UE, resource information indicating assigned resources of the unlicensed frequency band for communication between the base station and the UE,
transmit, to the UE, first information designating a first monitoring mode as a designated monitoring mode of determining whether the UE transmits a first signal in the unlicensed frequency band, and
receive, from the UE, the first signal within the unlicensed frequency band, the first signal transmitted by the UE by at least executing the first monitoring mode before transmitting the first signal using the assigned resources,
transmit, to the UE, second information designating a second mode as the mode of determining whether the UE transmits a second signal in the unlicensed frequency band,
receive, from the UE, the second signal within the unlicensed frequency band, the second signal transmitted by the UE by at least executing the second monitoring mode before transmitting the second signal using the assigned resources, wherein:
the first monitoring mode comprises the UE monitoring the unlicensed frequency band to check whether the unlicensed frequency band is in use, and
the second monitoring mode comprises the UE monitoring of the unlicensed frequency band without transmitting any signal in the unlicensed band, with reduced sensing of the unlicensed frequency band as compared to the first monitoring, to check whether the unlicensed frequency band is in use, the first monitoring mode and the second monitoring mode comprising a measurement of the same characteristics of the unlicensed frequency band.
15. A method comprising:
receiving, from a base station at a user equipment (UE), measurement configuration information via a licensed frequency band, wherein the measurement configuration information is information to instruct the UE to perform measurements on an unlicensed frequency band;
receiving, from the base station at the UE, resource information indicating assigned resources of the unlicensed frequency band for transmitting a first signal and a second signal to the base station, the resource information based on Received signal strength Indicator (RSSI) values of measurement results performed by the UE in accordance with the measurement configuration information;
receiving, from the base station at the UE, first information designating a first monitoring mode as a designated monitoring mode of determining whether the UE transmits a first signal in the unlicensed frequency band;
in response to receiving the first information, executing the first monitoring mode to perform first monitoring of the unlicensed frequency band to determine whether the unlicensed frequency band is in use;
in response to determining from the first monitoring that the unlicensed frequency band is not in use, transmitting the first signal including first data to the base station using the assigned resources of the unlicensed frequency band;
receiving, from the base station at the UE, second information designating a second monitoring mode as the designated monitoring mode of determining whether the UE transmits a second signal in the unlicensed frequency band;
in response to receiving the second information and before transmitting any signal in the unlicensed frequency band, executing the second monitoring mode to perform second monitoring of the unlicensed frequency band to determine whether the unlicensed frequency band is in use, the second monitoring performed without transmitting any signal in the unlicensed frequency band, the second monitoring of the unlicensed frequency band comprising reduced sensing of the unlicensed frequency band as compared to the first monitoring, the first monitoring and the second monitoring measuring the same characteristics of the unlicensed frequency band; and
in response to determining from the second monitoring that the unlicensed frequency band is not in use, transmitting the second signal including second data to the base station using the assigned resources of the unlicensed frequency band.
11. An apparatus for controlling a user equipment (UE), the apparatus comprising:
a memory; and
a controller, configured to cause the user equipment to:
receive, from a base station, measurement configuration information via a licensed frequency band, wherein the measurement configuration information is information to instruct the user equipment to perform measurements on an unlicensed frequency band;
perform measurements on the unlicensed frequency band in response to receiving the measurement configuration information from the base station, wherein the measurements include at least a measurement of Received signal strength Indicator (RSSI) values of the unlicensed frequency band;
transmit, to the base station, measurement results, wherein the measurement results include the RSSI values;
receive, from the base station, resource information indicating resources of the unlicensed frequency band for communication with the UE;
receive, from the base station, first information designating a first monitoring mode as a designated monitoring mode of determining whether the UE transmits a first signal in the unlicensed frequency band;
in response to receipt of the first information, execute the first monitoring mode to perform to determine whether the unlicensed frequency band is in use;
in response to a determination from the first monitoring mode that the unlicensed frequency band is not in use, transmit the first signal to the base station using the resources of the unlicensed frequency band;
receive, from the base station, second information designating a second monitoring mode as the designated monitoring mode of determining whether the UE transmits a second signal in the unlicensed frequency band;
in response to receipt of the second information and before transmission by the UE of any signal in the unlicensed frequency band, execute the second monitoring mode to determine whether the unlicensed frequency band is in use, the second monitoring performed without transmitting any signal in the unlicensed frequency band, the second monitoring mode of the unlicensed frequency band comprising reduced sensing of the unlicensed frequency band as compared to the first monitoring mode, the first monitoring mode and the second monitoring mode measuring the same characteristics of the unlicensed frequency band; and
in response to a determination from the second monitoring that the unlicensed frequency band is not in use, transmit the second signal to the base station using the resources of the unlicensed frequency band.
1. A method comprising:
receiving, from a base station at a user equipment (UE), measurement configuration information via a licensed frequency band, wherein the measurement configuration information is information to instruct the UE to perform measurements on an unlicensed frequency band;
performing measurements, at the UE, on the unlicensed frequency band in response to receiving the measurement configuration information from the base station, wherein the measurements include at least a measurement of Received signal strength Indicator (RSSI) values of the unlicensed frequency band;
transmitting, from the UE to the base station, measurement results, wherein the measurement results include the RSSI values;
receiving, from the base station at the UE, resource information indicating assigned resources of the unlicensed frequency band for communication between the base station and the UE;
receiving, from the base station at the UE, first information designating a first monitoring mode as a designated monitoring mode of determining whether the UE transmits a first signal in the unlicensed frequency band;
in response to receiving the first information, executing the first monitoring mode to perform first monitoring of the unlicensed frequency band to determine whether the unlicensed frequency band is in use;
in response to determining from the first monitoring that the unlicensed frequency band is not in use, transmitting the first signal to the base station using the assigned resources of the unlicensed frequency band;
receiving, from the base station at the UE, second information designating a second monitoring mode as the designated monitoring mode of determining whether the UE transmits a second signal in the unlicensed frequency band;
in response to receiving the second information and before transmitting any signal in the unlicensed frequency band, executing the second monitoring mode to perform second monitoring of the unlicensed frequency band to determine whether the unlicensed frequency band is in use, the second monitoring of the unlicensed frequency band comprising reduced sensing of the unlicensed frequency band as compared to the first monitoring, the second monitoring performed without transmitting any signal in the unlicensed frequency band, the first monitoring and the second monitoring measuring the same characteristics of the unlicensed frequency band; and
in response to determining from the second monitoring that the unlicensed frequency band is not in use, transmitting the second signal to the base station using the assigned resources of the unlicensed frequency band.
5. A user equipment (UE) comprising:
a transceiver configured to receive, from a base station, measurement configuration information via a licensed frequency band, wherein the measurement configuration information is information to instruct the user equipment to perform measurements on an unlicensed frequency band; and
a controller configured to:
perform measurements on the unlicensed frequency band in response to receiving the measurement configuration information from the base station, wherein the measurements include at least a measurement of Received signal strength Indicator (RSSI) values of the unlicensed frequency band,
wherein the transceiver is further configured to:
transmit, to the base station, measurement results, wherein the measurement results include the RSSI values,
receive, from the base station, resource information indicating resources of the unlicensed frequency band for communication between the base station and the UE,
receive, from the base station, first information designating a first monitoring mode as a designated monitoring mode of determining whether the UE transmits a first signal in the unlicensed frequency band,
in response to receipt of the first information, execute the first monitoring mode to perform first monitoring of the unlicensed frequency band to determine whether the unlicensed frequency band is in use;
in response to a determination from the first monitoring that the unlicensed frequency band is not is use, transmitting the first signal to the base station using the resources of the unlicensed frequency band;
receive, from the base station, second information designating a second monitoring mode as the designated monitoring mode of determining whether the UE transmits a second signal in the unlicensed frequency band;
in response to receipt of the second information and before transmission by the UE of any signal in the unlicensed frequency band, execute the second monitoring mode to perform second monitoring of the unlicensed frequency band to determine whether the unlicensed frequency band is in use, the second monitoring performed without transmitting any signal in the unlicensed frequency band, the second monitoring of the unlicensed frequency band comprising reduced sensing of the unlicensed frequency band as compared to the first monitoring, the first monitoring and the second monitoring measuring the same characteristics of the unlicensed frequency band; and
in response to a determination from the second monitoring that the unlicensed frequency band is not in use, transmit the second signal to the base station using the resources of the unlicensed frequency band.
13. A user equipment (UE) comprising:
a transceiver configured to receive, from a base station, measurement configuration information via a licensed frequency band, wherein the measurement configuration information is information to instruct the user equipment to perform measurements on an unlicensed frequency band; and
a controller configured to:
perform measurements on the unlicensed frequency band in response to receiving the measurement configuration information from the base station, wherein the measurements include at least a measurement of Received signal strength Indicator (RSSI) values of the unlicensed frequency band,
wherein the transceiver is further configured to:
transmit, to the base station, measurement results including the RSSI values,
receive, from the base station, resource information indicating assigned resources of the unlicensed frequency band for at least transmission of a first signal and a second signal from the UE to the base station,
receive, from the base station, first information designating a first monitoring mode as a designated monitoring mode of determining whether the UE transmits the first signal in the unlicensed frequency band to the base station,
in response to receipt of the first information, execute the first monitoring mode to perform first monitoring of the unlicensed frequency band to determine whether the unlicensed frequency band is in use;
in response to a determination from the first monitoring that the unlicensed frequency band is not is use, transmit the first signal comprising first data to the base station using the assigned resources of the unlicensed frequency band;
receive, from the base station, second information designating a second monitoring mode as the designated monitoring mode of determining whether the UE transmits a second signal in the unlicensed frequency band to the base station;
in response to receipt of the second information and before transmission by the UE of any signal in the unlicensed frequency band, execute the second monitoring mode to perform second monitoring of the unlicensed frequency band to determine whether the unlicensed frequency band is in use, the second monitoring of the unlicensed frequency band comprising reduced sensing of the unlicensed frequency band as compared to the first monitoring without transmitting any signal in the unlicensed frequency band, the first monitoring and the second monitoring measuring the same characteristics of the unlicensed frequency band; and
in response to a determination from the second monitoring that the unlicensed frequency band is not in use, transmit the second signal comprising second data to the base station using the assigned resources of the unlicensed frequency band.
2. The method of
3. The method of
4. The method of
the measurement configuration information comprises information instructing the UE to perform measurements on the unlicensed frequency band at a measurement periodicity and for a measurement time period and specifying the measurement periodicity and measurement time period for RSSI measurements; and
the measurements include at least measurements of RSSI values of the unlicensed frequency band at the measurement periodicity and for the measurement time period.
6. The UE of
7. The UE of
the measurement configuration information comprises information instructing the UE to perform measurements on the unlicensed frequency band at a measurement periodicity and for a measurement time period and specifying the measurement periodicity and measurement time period for RSSI measurements; and
the measurements include at least measurements of RSSI values of the unlicensed frequency band at the measurement periodicity and for the measurement time period.
9. The base station of
10. The base station of
the measurement configuration information comprises information instructing the UE to perform measurements on the unlicensed frequency band at a measurement periodicity and for a measurement time period and specifying the measurement periodicity and measurement time period for RSSI measurements; and
the measurements results include at least measurement results of measurements of RSSI values of the unlicensed frequency band at the measurement periodicity and for the measurement time period.
12. The apparatus of
the measurement configuration information comprises information instructing the UE to perform measurements on the unlicensed frequency band at a measurement periodicity and for a measurement time period and specifying the measurement periodicity and measurement time period for RSSI measurements; and
the measurements include at least measurements of RSSI values of the unlicensed frequency band at the measurement periodicity and for the measurement time period.
14. The UE of
the measurement configuration information comprises information instructing the UE to perform measurements on the unlicensed frequency band at a measurement periodicity and for a measurement time period and specifying the measurement periodicity and measurement time period for RSSI measurements; and
the measurements include at least measurements of RSSI values of the unlicensed frequency band at the measurement periodicity and for the measurement time period.
16. The method of
the measurement configuration information comprises information instructing the UE to perform measurements on the unlicensed frequency band at a measurement periodicity and for a measurement time period and specifying the measurement periodicity and measurement time period for RSSI measurements; and
the measurements results include at least measurement results of measurements of RSSI values of the unlicensed frequency band at the measurement periodicity and for the measurement time period.
17. The method of
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The present application claims priority to Provisional Application No. 62/002,037, entitled “METHODS OF RESERVING RESOURCES ON UNLICENSED BANDS”, filed May 22, 2014, and to Provisional Application No. 62/002,041, entitled “METHODS OF COORDINATING LTE TRANSMISSIONS ON UNLICENSED BANDS”, filed May 22, 2014, both assigned to the assignee hereof, and hereby expressly incorporated by reference.
The present application claims is related to PCT Patent Application No. PCT/US2015/032257 entitled “UNLICENSED FREQUENCY BAND WITH LICENSED FREQUENCY BAND TIMING”, PCT Patent Application No. PCT/US2015/032265 entitled “COMMUNICATION RESOURCE SCHEDULING FOR DEVICE-TO-DEVICE (D2D) COMMUNICATION IN AN UNLICENSED FREQUENCY BAND”and PCT Patent Application No. PCT/US2015/032279 entitled “PHYSICAL CHANNEL STRUCTURE FOR COMMUNICATION IN UNLICENSED FREQUENCY BAND”, all filed concurrently with this application, assigned to the assignee hereof, and hereby expressly incorporated by reference.
This invention generally relates to wireless communications and more particularly to assigning unused communication resources in an unlicensed frequency band equipment operating in a licensed frequency band.
The frequency spectrum used by a particular communication system may be licensed or unlicensed. Licensed frequency spectrum (frequency band) is licensed to a system operator by a government agency such as the Federal Communications Commission (FCC). An example of such licensed spectrum includes frequency bands used for cellular communication. An unlicensed frequency band is any portion of frequency spectrum that does not require a license from the government agency to communicate with the unlicensed frequency band. Equipment operating within the unlicensed band, however, typically must adhere to regulations and/or communication standards. An example of unlicensed frequency spectrum includes frequency bands used for Institute of Electrical and Electronics Engineers (IEEE) 802.11 communication.
Communication equipment communicating in a licensed frequency band identifies unused unlicensed communication resources within an unlicensed frequency band. The communication equipment uses the identified unlicensed communication resources to communicate within the unlicensed frequency band. In some circumstances, the unused unlicensed communication resources are identified based on resource information received from a base station where the resource information identifies unlicensed communication resources that will be used by the base station. In other circumstances, the unused unlicensed communication resources are identified based on frequency band measurements of the unlicensed frequency band over an observation time duration longer than a sensing time duration used by unlicensed equipment using the unlicensed frequency band.
A cellular communication system is typically required to adhere to a communication standard or specification. The communication specification defines physical channel structure that at least includes a data channel and a control channel for uplink and downlink transmissions and specifies at least some timing and frequency parameters for physical downlink control channels from a base station to a wireless communication device. The Third-Generation Partnership Project Long-Term Evolution (3GPP LTE) communication specification is a specification for systems where communication stations (eNodeBs) provide service to wireless communication devices (UE devices) using orthogonal frequency-division multiple access (OFDMA) on the downlink and single-carrier frequency-division multiple access (SC-FDMA) on the uplink. Although the techniques described herein may be applied in other types of communication systems, the exemplary systems discussed herein operate in accordance with an FDD 3GPP LTE communication specification.
The eNB 104 can be any type of communication station or transceiver station or radio head and may be referred to as a base station, eNodeB, fixed station, access point, and other terms. The eNB 104 may be connected within a network of several other eNBs through a backhaul (not shown in
The licensed communication equipment communicates in the licensed frequency band using a licensed physical channel structure. The physical channel structure for downlink communication may differ from the physical channel structure for uplink communication. The licensed physical channel structure partitions time and frequency to define a plurality of time-frequency resources (resource elements). Sets of resources are allocated for a particular type of communication. For example, different sets of time-frequency communication resources can be allocated for data, control, and reference signals. For the examples herein, the licensed physical channel structure adheres to at least one revision of the 3GPP LTE communication specification.
Other unlicensed devices 112, 114, 116, 118 within the licensed service area 102 use an unlicensed frequency band for communication. The unlicensed devices 112, 114, 116, 118 may include access points 112 providing service to mobile devices 114 and devices 116, 118 operating in device-to-device communication scenarios. The unlicensed communications may be ad hoc communication scenarios and may be bidirectional or one way. Accordingly, the unlicensed devices 112, 114, 116, 118 may include various types of devices and equipment. For the example of
For the examples herein, the licensed equipment 104, 106, 108, 110 uses an unlicensed physical channel structure for communication in the unlicensed frequency band where the unlicensed physical channel structure at least has the same time and frequency divisions as the licensed physical channel structure. Although the frequencies are different, each frequency division in the unlicensed structure corresponds to a frequency division in the licensed structure such that the communication resource elements in the unlicensed structure correlate to the communication resource elements in the licensed structure. A reference set of communication resource elements for transmission of reference signals have the same symbol times as a reference set of resource elements allocated in the licensed physical channel structure for reference signals. Other arrangements may be used in some circumstances. An example of physical channel structure related to licensed and unlicensed communication is discussed in PCT Patent Application No. PCT/US2015/032279, entitled “Physical Channel Structure For Communication In Unlicensed Frequency Band”, and filed concurrently with this application.
For the examples herein, the licensed equipment 104, 106, 108, 110 uses the unlicensed frequency band for communication at times determined to avoid interference or at least to result in a tolerable level of interference with communication between unlicensed devices and, in some situations, other licensed devices using the unlicensed frequency band. When it is determined that unlicensed equipment is operating nearby, the unlicensed frequency band is monitored prior to transmission to determine if the band is currently in use. If it is determined that the band is not in use, the licensed equipment transmits signals within the unlicensed frequency band. The monitoring procedure prior to transmission is the same, or at least similar to the sensing/back off procedures employed by conventional devices operating in the unlicensed frequency band. The techniques may be required by rules or standards governing operation in the unlicensed frequency band. For the example of
In one example, eNBs provide unlicensed resource information to other nearby eNBs where the unlicensed resource information identifies the unlicensed communication resources that are being, or will be, used for communication in the unlicensed frequency band. The eNBs receiving the resource information identify unused unlicensed resources based on the resource information and use unlicensed communication resources least likely to cause interference.
In other examples, as discussed in further detail below, on observation procedure is performed by one or more eNBs and/or one or more UE devices. Frequency band measurements are taken by one or more eNBs and/or one or more UE devices to determine if it is likely that the unlicensed frequency band is in used by other equipment sufficiently close to result in interference. The unlicensed frequency band is observed for a relatively long period of time as compared to conventional sensing techniques used prior to a transmission in the unlicensed frequency band. For example, the unlicensed frequency band may be monitored on the order of hours. The energy within the unlicensed frequency band is measured and compared to a threshold. If the energy level is below a threshold (e.g., no interference is detected), it is determined that no nearby equipment is using the unlicensed frequency band and the licensed equipment operates in a non-sensing mode where the sensing/monitoring of unlicensed frequency band before transmission is omitted or at least reduced. The non-sensing mode differs from a sensing mode where devices sense or monitor one or more channels before transmitting a signal in the unlicensed frequency band. The sensing mode, therefore, is employed when it is confirmed that other nearby devices are using the unlicensed frequency band for communication or when it cannot be determined that no devices are using the unlicensed frequency band.
For the examples herein, the frequency band measurements of the observation procedure also differ from conventional listen-before-talk sensing techniques in that the interference measurements are based on the entire, or nearly entire, unlicensed frequency band. Conventional sensing techniques sense particular channels within the unlicensed frequency band to detect potential signals. In contrast, for the examples herein, the unlicensed frequency band is observed to detect any energy anywhere in the band that may indicate the band is in use.
The eNB may execute the observation procedure by making the frequency band measurements and/or may instruct one or more UE devices to perform the observation procedure by taking frequency band measurements and reporting the results to the eNB. For the example discussed with reference to
The licensed band transceiver 202 includes a transmitter that transmits uplink wireless signals to eNBs and a receiver that receives downlink wireless signals from the eNBs within the licensed frequency band. The transceiver can also be configured to transmit and receive D2D signals using allocated licensed uplink communication resources. The controller 204 controls components of the UE device 200 to manage the functions of the device 200 described herein as well as to facilitate the overall functionality of the device 200. The controller 204 is connected to the transceivers 202, 206 and other components such as memory.
The unlicensed band receiver 208 may be used to sense/monitor the unlicensed frequency band before a transmission in the unlicensed frequency band when the UE device is operating in the sensing mode. In addition, the unlicensed band receiver 208 may be used to perform the observation procedure. For the examples, the controller and the unlicensed band receiver 208 measure one or parameters that indicate the energy level within the unlicensed frequency band. An example of a suitable technique includes determining the received signal strength indicator (RSSI) which is a measurement of the power present in the received radio signal. The RSSI is compared to a threshold.
As discussed below, the unlicensed band receiver 208 is also used to measure channel conditions of the unlicensed frequency band during the non-sensing mode. Using techniques at least similar (if not the same) as the techniques used in the licensed frequency band for radio resource management (RRM) measurements.
The licensed band transceiver 302, therefore, includes at least a downlink transmitter for transmitting downlink signals and an uplink receiver for receiving uplink signals. In some situations, the licensed band transceiver also includes downlink receiver. As discussed below, eNBs may wirelessly transmit unlicensed frequency band communication resource information in a downlink broadcast message for receipt by other nearby eNBs. Accordingly, the downlink receiver in the eNB 300 receives downlink signals from other eNBs.
The unlicensed band receiver 308 may be used to sense/monitor the unlicensed frequency band before a transmission in the unlicensed frequency band when the eNB is operating in the sensing mode. In addition, the unlicensed band receiver 308 may be used to perform the observation procedure. For the examples, the controller and the unlicensed band receiver 308 measure one or parameters that indicate the energy level within the unlicensed frequency band. An example of a suitable technique includes determining the received signal strength indicator (RSSI) which is a measurement of the power present in the received radio signal. The RSSI is compared to a threshold. The threshold used by the eNB is typically the same as the threshold used by UE devices although in some circumstances the thresholds may be different.
For the example, the eNB 300 also includes a communication interface 312 for facilitating communication over the backhaul with other eNBs and network entities. Where X2 signaling is available, the communication interface 312 communicates over the backhaul using X2.
In some situations, the first eNB 402 is connected to the second eNB through a backhaul 414. The backhaul can utilize any combination of wired and wireless communication links to establish communication between the eNBs. The backhaul 414, for example, may include radio frequency and point-to-point microwave links and transmission hardware such as transmitters, receivers, wires, coaxial cables, fiber optic cables, and other known devices and equipment. In some circumstance, the backhaul supports X2 signaling and/or packet data protocols such as those used with the Internet. Where a backhaul is available, the first eNB transmits the unlicensed frequency band resource information over the backhaul 414 by applying techniques in accordance with conventional signaling over a backhaul. An X2 message, for example, can be sent including the unlicensed frequency band communication resource information.
In situations where the eNBs are not connected through a backhaul, the first eNB 402 provides unlicensed frequency band communication resource information 406 to nearby eNBs (404) by broadcasting the unlicensed frequency band communication resource information over a wireless channel 416. An example of a suitable technique of broadcasting the information 406 in an LTE system includes transmitting a System Information Blocks (SIB) message including the information 406. Since SIBs are transmitted in the downlink channel, the nearby eNBs 404 receive the SIB signals using a downlink receiver.
In another example, the first eNB 402 broadcasts the unlicensed frequency band communication resource information in the uplink channel. An example of suitable technique for broadcasting the unlicensed frequency band communication resource information on the uplink channel includes using a D2D channel defined by some revisions of the LTE standard. For example a broadcasts message similar to a D2D discovery signal can be sent from the eNB 402.
After receiving the unlicensed frequency band communication resource information 406, the second eNB 404 identifies which communication resources within the unlicensed frequency band are not in use. These unused unlicensed frequency band resources can then be used by the second eNB 404 to communicate with one or more UE devices 418 over a wireless channel 420 in the unlicensed frequency band. Generally, the unlicensed frequency band resources identified in the unlicensed frequency band communication resource information are not used by the eNB 404. Therefore, the first eNB 402 reserves unlicensed frequency band resources for communication minimizing interference in the unlicensed frequency band. In some situations, the second eNB 404 may respond to the first eNB 402 with an indication that identified resources should not be used by the first eNB 402. Such a situation may occur where the second eNB 402 requires the resources for high priority communication such as E911. Although not shown in
Although various measurement timings and techniques can be used, the timing should be selected such that the likelihood that a device is using the unlicensed frequency band but is not detected is minimized. For example, the time period between measurements should not have a length such that a device could transmit between measurements and not be detected. The time period between measurements can be dynamic and, in some situations, be varied depending on current circumstances. Unlike for the case of RSRP/RSRQ measurements for LTE in licensed bands, there are no specific reference signals that the device is measuring in predefined subframe locations. The eNB should specify the periodicity and time period of each RSSI measurement. The eNB may determine the current periodicity and time period of the RSSI measurements using observed traffic patterns from e.g., APs in the unlicensed band. Alternatively, the eNB may configure measurement gaps to the device to allow the UE device to perform RSSI measurements based on these measurement gaps. The UE device may also perform RSSI measurements using Autonomous Gaps. If autonomous gaps are used to perform measurements, the UE is allowed to temporarily abort communication with all serving cell(s), i.e., create autonomous gaps to perform the corresponding measurements within the limits specified in TS 36.133 [16]. In yet another mode of operation, the UE device with multiple receivers may continuously measure the RSSI signal for the entire duration of the measurement request from the eNB (e.g., 1 hour) in the specified frequency/band without any impact to its cellular reception. The UE may determine such measurement based on its reserved battery power remaining. Other signal measurements can also be used. Examples of other forms of measurements include BeaconRSSI, RCPI (Received channel power indicator) and RSNI (Received Signal to Noise Indicator) that are specific to WLAN in case the eNB is already aware of the type of interference expected in the region.
For the example, channel access procedure used in the unlicensed frequency band is a sense and back-off procedure (sense/back-off procedure) where the unlicensed frequency band is monitored 604 for a sensing time duration 605 and, if no other devices are determined to be using the band, the eNB waits a back-off period 606 before transmitting. The back-off period 606 is dynamic and may be determined by a formula typically applied by unlicensed equipment in the unlicensed band. The sensing time duration 605 is typically on the order of tens of microseconds.
The licensed equipment observing device 502 performs an observation procedure 610 for an observation time duration 612. As discussed above, the licensed equipment 502 continually (or periodically at a sufficient frequency) compares received signal energy in the unlicensed frequency band to a threshold. If the threshold is exceeded, it is determined that other equipment using the unlicensed frequency band is sufficiently close to create interference. As illustrated in
The UE device 702 observes the unlicensed frequency band by taking frequency band measurements and, if the detected energy is below the threshold for a sufficiently long time, determines that the unlicensed frequency band is not being used by any nearby equipment. For the examples herein, the UE device 702 reports the results in frequency band measurement information 724 to its serving eNB 726. The eNB 726, at least partially based on the frequency band measurement information 724, determines whether communications 728 in the unlicensed frequency band should be modified. For example, the eNB 726 may determine that the eNB and UE device can operate in a non-sensing mode where the equipment does not employ a sense/back-off procedure before transmitting in the unlicensed frequency band. An example of suitable technique includes operating in the unlicensed frequency band with the same channel access protocol used in the licensed frequency band. The eNB 726 and the UE device 702, therefore, operate in sensing mode when the unlicensed frequency band is being used by other nearby equipment and operate in a non-sensing mode when it is determined that the unlicensed frequency band is not being used by other equipment.
The frequency band measurement information 724 is indicative of the frequency band measurements taken by the UE device. In some situations, frequency band measurement information 724 is indicative of a comparison of one or more measured energy levels to the threshold. For example, the frequency band measurement information 724 may simply be a flag indicating that the energy level has exceeded the threshold within the observation time period. In other situations, the frequency band measurement information 724 may be measurements, values, or data based on measurement values which can be used by the eNB to make determinations regarding the use of the unlicensed frequency band by other devices.
The eNB 726 monitors the unlicensed frequency band and, if the detected energy is below the threshold for a sufficiently long time, determines that the unlicensed frequency band is not being used by any nearby equipment. The eNB 726, at least partially based on the measurements of the unlicensed frequency band, determines whether communications in the unlicensed frequency band should be modified. For example, the eNB 726 may determine that the eNB and UE device can operate in the non-sensing mode where the equipment does not employ a sense/back-off procedure before transmitting in the unlicensed frequency band.
In many circumstances, the eNB 726 bases the determination on multiple interference measurement reports receives from multiple UE devices as well as on its own measurements of the unlicensed frequency band. The eNB 726 may approach the use of the non-sensing mode more conservatively. In case any UE device reports a measurement above the threshold the eNB 726 should not apply the non-sensing mode. Another technique includes having coordination among eNBs whereby the first eNB 402 informs the second eNB 404 in case eNB 402 detects interference in the unlicensed band but the second eNB 404 does not. This technique assumes that the two eNBs are in close proximity.
The eNB 726 and the UE device 702 continue to monitor the unlicensed frequency band when in the non-sensing mode. In one example, UE devices operating in the non-sensing mode perform Radio Resource Management (RRM) measurements of the unlicensed frequency band and report the RRM measurements to the eNB 726. The eNB 726 configures one or more thresholds in the UE devices either by broadcast (SIB) or dedicated controls signals. The thresholds may include one or more of a radio signal strength indicator (RSSI), a received channel power indicator (RCPI), a received signal to noise indicator (RSNI), and an average noise plus interference (ANPI) indicator. The eNB compares the reported RRM measurements to thresholds and makes an assessment of the channel characteristics. In some situations, the channel characteristics may indicate a potential interferer which triggers the eNB to return to sensing mode, perform the frequency band observation procedure, and/or instruct one or more UE devices to perform the frequency band observation procedure.
At step 902, the eNB performs a frequency band observation procedure on the unlicensed frequency band. The eNB periodically measures the energy level within the unlicensed frequency band for the observation time. As discussed above, an example of a suitable technique of observing the band includes measuring RSSI over for the entire band and comparing the level to a threshold.
At step 904, if the energy level exceeds a threshold, the eNB determines that other devices are transmitting within the unlicensed frequency band. If other devices are using the unlicensed frequency band, the method continues at step 906. Otherwise, the method continues at step 908.
At step 906, the system communicates in the unlicensed frequency band 906 in the sensing mode. Since other devices are using the unlicensed frequency band, the licensed equipment (eNB and UE devices) must sense the band before transmitting. The method returns to step 902 to perform the observation procedure. Although the eNB can immediately begin the procedure, it some circumstances the eNB can delay before beginning the procedure. The eNB could, for example, wait at least an hour before performing step 902. Delaying is not critical for the eNB since the eNB is not power constrained. Therefore, even continuous measurement is not a significant consideration for the eNB in most circumstances. The length of the delay may be based on a fixed time or may be based on other factors. For example, when measured channel quality is above a threshold, the eNB may perform the observation procedure.
At step 908, the eNB instructs one or more UE devices to perform a frequency band observation procedure. Although the eNB has not detected significant energy in the unlicensed frequency band, it is possible that other devices are operating in the unlicensed frequency band. Such a situation is often referred to as the “hidden node”. The UE devices are more likely to detect the energy of these other devices in these cases. In some situations, the UE devices and the eNB may perform their observation procedures simultaneously or at least have overlapping observation times. In most situations, in order to avoid unnecessary power consumption by the UE devices, the eNB does not instruct the UE devices to perform the observation procedure until a relatively high confidence level that no other devices are present is achieved.
At step 910, the eNB receives, from the one or more UE devices, the results of the observation procedures performed by the UE devices. For the example, the UE devices transmit frequency band measurement information indicative of the observation procedure measurements. The information includes measurements or information based on measurements. For example, the results may include information regarding whether the UE device has determined whether or not other devices are using the unlicensed frequency band. When performing the observation procedure for the examples herein, each UE device periodically measures the RSSI over an observation period, compares the RSSI levels to a threshold, and reports to the eNB the results. The observation times and the thresholds of the UE devices and the eNB may be the same or may be different, depending on the particular implementation. The UE devices, however may report the measurements or other information in some situations.
A step 912, the eNB determines whether the unlicensed frequency band is in use by other devices. The eNB makes the determination at least partially based on the results received from one or more of the UE devices. Where the results indicate that an UE device has determined that the energy level has exceeded the threshold and other devices are using the unlicensed frequency band, the eNB determines that the band is in use. Where measurements or other less definitive information is provided by the UE devices, the eNB processes the information to determine whether the unlicensed frequency band is in use by other devices. The eNB may process the information from each UE device individually or may process the information from multiple UE devices collectively. In some situations, the eNB may include measurements taken at the eNB when evaluating the results provided by the UE devices and determining whether the unlicensed frequency band is in use by other devices. If it is determined that the unlicensed frequency band is in use by other devices, the method returns to step 906. Otherwise, the method continues at step 914.
At step 914, the system operates in the unlicensed frequency band in the non-sensing mode. The eNB instructs the UE devices to operate in the non-sensing mode starting at a particular frame, subframe, or time. The eNB and the UE devices do not sense the unlicensed frequency band before transmissions as dictated by the rules or standards governing the unlicensed frequency band. Rather, the licensed equipment operates similarly to the operation in the licensed frequency band. For example, the techniques used in an LTE system operating in accordance with one or more revision of the 3GPP LTE standard are used to communicate in the unlicensed frequency band (at the different frequencies).
At step 916, the eNB receives RRM measurements from the UE devices. For the examples, the eNB receives the RRM measurement while the system is communicating in the non-sensing mode (step 914). For the example, the RRM measurements are the same RRM measurements taken and reported by the UE devices when operating in the licensed frequency band except that the measurements are taken at the different frequencies of the unlicensed frequency band.
At step 918, the eNB determines whether the frequency band observation procedure should be performed by the eNB. The determination may be based on several factors or combination of factors including, but not limited to, RRM measurements, channel characteristics, elapsed time since the eNB has performed the observation procedure, and the elapsed time since an eNB as performed an observation procedure. If it is determined that the observation procedure should be performed, the method returns to step 902. Otherwise, the method continues at step 920. As discussed above, the observation procedure may be performed by the UE device and the eNB at the same time in some circumstances. Where the decision to perform the observation procedure is based on RRM measurements from the UE devices, the eNB may determine that the UE device should perform the observation procedure at step 902.
At step 920, the eNB determines whether the frequency band observation procedure should be performed at one or more UE devices. The determination may be based on several factors or combination of factors including, but not limited to, RRM measurements, channel characteristics, elapsed time since the eNB has performed the observation procedure, and the elapsed time since an eNB as performed an observation procedure. If it is determined that the observation procedure should be performed, the method returns to step 908. Otherwise, the method returns to step 914. As discussed above, the observation procedure may be performed by the UE device and the eNB and the same time in some circumstances. The eNB may determine that the eNB should also perform the observation procedure at step 908.
At step 1002, the UE device operates in the sensing mode in the unlicensed frequency band. Accordingly, the UE device monitored the unlicensed frequency band before transmission in the unlicensed frequency band.
At step 1004, the UE device determines if an instruction has been received from the eNB to perform frequency band observation procedure. If an instruction has been received, the method continues at step 1006. Otherwise, the method returns to step 1002.
A step 1006, the UE device performs the frequency band observation procedure. As discussed above, the UE device measures the energy in the unlicensed frequency band for an observation time. The UE device may measure RSSI for the band, for example.
At step 1008, the UE device reports the results of the observation procedure. For the example, the results include a determination of whether the RSSI level exceeded a threshold. In some circumstances, however, results of the observation procedure may include the RSSI measurements and/or other information.
At step 1010, the UE device determines if an instruction to operate in the non-sensing mode has been received. If the eNB instructs the UE device to operate in the non-sensing mode, the UE device continues at step 1012 where the device operates in the non-sensing mode. Otherwise, the method returns to step 1002.
At step 1014 and 1016, the UE device performs and reports RRM measurements to the eNB while operating in the sensing mode. As discussed above, the RRM measurement procedure is similar to the procedure followed in the licensed frequency band.
At step 1018, the UE device determines whether an instruction has been received to operate in the sensing mode. If an instruction has been received, the method returns to step 1002. Otherwise, the method continues at step 1020.
At step 1020, the eNB determines whether an instruction has been received to perform the observation procedure. If an instruction has been received, the method proceeds to step 1022. Otherwise, the method returns to step 1012.
At step 1022, the UE performs the observation procedure and reports the results at step 1024. In some situations, the eNB instructs the UE device to operate in the sensing mode when performing the observation procedure, and in other situations, the UE device continues operating in the non-sensing mode, reporting RRM measurements and performing the observation procedure.
Clearly, other embodiments and modifications of this invention will occur readily to those of ordinary skill in the art in view of these teachings. The above description is illustrative and not restrictive. This invention is to be limited only by the following claims, which include all such embodiments and modifications when viewed in conjunction with the above specification and accompanying drawings. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.
| Patent | Priority | Assignee | Title |
| 11743753, | Apr 01 2016 | Telefonaktiebolaget LM Ericsson (publ) | Methods for controlling relative measurements in the presence of LBT |
| Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
| Sep 16 2014 | KALHAN, AMIT | Kyocera Corporation | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 040347 | /0713 | |
| Sep 16 2014 | CHANG, HENRY | Kyocera Corporation | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 040347 | /0713 | |
| Sep 16 2014 | COMSTOCK, DAVID | Kyocera Corporation | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 040347 | /0713 | |
| May 22 2015 | Kyocera Corporation | (assignment on the face of the patent) | / |
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